The deepest musical note ever generated in space - a B flat one million billion times deeper than can be heard by humans - has been recorded at a black hole and it's estimated that it has been sounding for 2.5 billion years.

NASA's Chandra X-Ray Observatory discovered the note, 57 octaves below the middle keys of a piano, in the Perseus cluster. Astronomers believe that the discovery of the sound could help them understand how the universe's largest structures - galaxy clusters - evolve.

The data processed by Chandra revealed sound waves rippling through the hot gas of the Perseus cluster. Special image processing technique were used to bring out subtle changes in brightness.

250 million light years away, the gas in the Perseus galaxy is apparently being heated by the B-flat, which begins to explain why gas surrounding the cluster does not cool down.

However, astronomers were apparently not surprised to find sound being generated at the black hole. Despite their characteristic image of being dark and invisible, black holes create bright and chaotic environments and radiation from radio waves to visible light to X-rays have all been recorded.

Previous studies have shown that due to the huge amounts of activity around black holes, many notes are often created, producing a discordant inaudible symphony of space music.